WebUI: Polymer config tweaks for better performance.

chrome/browser/resources/md_downloads/focus_row.js

-// Copyright 2015 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-cr.define('downloads', function() {
-  /**
-   * @param {!Element} root
-   * @param {?Node} boundary
-   * @constructor
-   * @extends {cr.ui.FocusRow}
-   */
-  function FocusRow(root, boundary) {
-    cr.ui.FocusRow.call(this, root, boundary);
-    this.addItems();
-  }
-
-  FocusRow.prototype = {
-    __proto__: cr.ui.FocusRow.prototype,
-
-    addItems: function() {
-      this.destroy();
-
-      this.addItem('name-file-link',
-          'content.is-active:not(.show-progress):not(.dangerous) #name');
-      assert(this.addItem('name-file-link', '#file-link'));
-      assert(this.addItem('url', '#url'));
-      this.addItem('show-retry', '#show');
-      this.addItem('show-retry', '#retry');
-      this.addItem('pause-resume', '#pause');
-      this.addItem('pause-resume', '#resume');
-      this.addItem('cancel', '#cancel');
-      this.addItem('controlled-by', '#controlled-by a');
-      this.addItem('danger-remove-discard', '#discard');
-      this.addItem('restore-save', '#save');
-      this.addItem('danger-remove-discard', '#danger-remove');
-      this.addItem('restore-save', '#restore');
-      assert(this.addItem('remove', '#remove'));
-
-      // TODO(dbeam): it would be nice to do this asynchronously (so if multiple
-      // templates get rendered we only re-add once), but Manager#updateItem_()
-      // relies on the DOM being re-rendered synchronously.
-      this.eventTracker.add(this.root, 'dom-change', this.addItems.bind(this));
-    },
-  };
-
-  return {FocusRow: FocusRow};
-});